Results 1 to 20 of 20

Thread: DIY: Pre-fan delete mod: auxiliary fan circuit testing

  1. #1
    Join Date
    Apr 2005
    Location
    Bangkok, Thailand
    Posts
    254
    My Cars
    94E36 m42 SEDAN

    Thumbs up DIY: Pre-fan delete mod: auxiliary fan circuit testing

    After been tried out of doing a FDM, I think the following procedures should be conducted prior this MOD and should be told though.

    The most important thing before we gonna do the mod. I strongly recommend you to test the e-fan circuit first. So, we don't mess up with overheating because of the electrical faulty right at the beginning.


    Hereafter, I will refer to "0", "T1", and "T2" as these assigned temp switching sensor pins as above.


    According to the Bentley manual on my 1994 318 wiring diagram above, It implied that
    • When the temp reached T1, temp setting level-1, the contact in T1 terminal will engage with 0 terminal that provides a negative/chassis ground to the low/normal speed fan relay. Then, lo-speed fan operates. In addition, the lo-speed fan will also go on when the a/c compressor functions.
    • Consequently, after the temp progressed to T2, temp setting level-2, the contact in T2 terminal will engage with 0 terminal that provides a negative/chassis ground to the hi-speed fan relay. Then, hi-speed fan operates. On my 1994 318 the hi-speed fan only function by T2 trigger, water temp sensor switch.


    Sensor plug terminal allocation in my car is like this:



    Let's begin the test:
    1. While motor is running/idling and a/c turns off, detach the sensor plug.


    2.Make a tip spice-off wire like this


    3.Insert the wire tips into terminal 0 and T1 as in the shown pics.


    The lo-speed fan must operates.


    4.continued with T2


    Hi-speed fan must operates.

    If your fan neither lo nor hi speed not working, DO NOT DO THE FDM !!!!!
    All failures must be identified and repaired first. There might be, i.e., wiring failure, terminal socket failure, relay failure, and/or the fan failure.

    Have a great day,
    God bless you all
    -George
    Last edited by psyyambmw; 07-07-2011 at 11:00 PM.

  2. #2
    Join Date
    Nov 2008
    Location
    Sacramento, CA
    Posts
    1,408
    My Cars
    540it-318ti-318ic-Z3
    George, nice reference! Thank you for putting this together!

    Do you know what the temp trigger points are for T1 and T2?

    Thanks!

    1999 540it - Schwartz II/Sand Beige, style 5 rims, Conti DWS 235/45 tires, Billy HD/Sports, Stoptech S/S BL, F1 Pinacle 35% tint, Zionsville Cooling kit
    1998 318ti Cali Sport - Schwartz II/Schwartz Anthratz, staggered style 23
    1997 318ti Sport - Schwartz II/Schwartz Anthratz, staggered style 68 ,

    1995 318ti Active - Alpineweib III/Schwartz, squared style 32
    1994 325i - Bostongrau/Tan, Billy Sports, H&R springs
    1991 318ic - Schwarz/Anthratz Stoff, Bilstien HD, Z4 3.0 SS, Magnaflow, S/S Stress bar, x-brace, M20 FW, Elipsoid/HID, K&N

    BMWCCA# 160411

    1995 318ti Sport Schwartz II/Schwartz Anthratz - Sold
    1985 635CSI - Schwartz\Sand - Sold

    1984 533i "Max" - Schwarz/Schwarz, - Sold
    1984 318i - Champagne/Tan, Stock - Sold

  3. #3
    Join Date
    Jun 2011
    Location
    North Alabama
    Posts
    1,919
    My Cars
    1998 BMW 323IS

    Tag

    Ffr

  4. #4
    Join Date
    Apr 2005
    Location
    Bangkok, Thailand
    Posts
    254
    My Cars
    94E36 m42 SEDAN
    Quote Originally Posted by BlackBMWs View Post
    George, nice reference! Thank you for putting this together!

    Do you know what the temp trigger points are for T1 and T2?

    Thanks!
    80/88 for the TI and 91/99 for the rest of e36. Of course, I put 80/88 on mine though.
    Last edited by psyyambmw; 05-09-2012 at 09:47 AM.

  5. #5
    Join Date
    Jun 2009
    Location
    Kansas
    Posts
    503
    My Cars
    1994 353is 1995 M3
    hey, I know this thread is a little old but I need some help here with my AUX fan....

    Here's the quick back story, I did the FDM a while back, everything was peachy,
    but eventually my AUX started making some noise, but I ignored it like a boss.

    Later, in the insane heat of a kansas summer, a magnet came loose in the fan motor and locked up the motor....
    I then bought a used motor off a parts car and threw it in, only to find out the fan still didn't work.

    HERES the details, I just tested the motor today and it works high and low on its own.
    I took the plug off the radiator temp sensor and bridge both connections and neither works.
    So here is my question, did BOTH of my relays burn out at the same time the motor let go? or did a wire burn up because the motor was locked and shorting the system??

    I will try to find some replacement relays locally in the meantime, but I would appreciate some input from the BF.c community....

    thanks guys

  6. #6
    Join Date
    May 2011
    Location
    San Diego
    Posts
    285
    My Cars
    03 Z4 / 12 X5
    Quote Originally Posted by Bowze View Post
    So here is my question, did BOTH of my relays burn out at the same time the motor let go? or did a wire burn up because the motor was locked and shorting the system??
    Did you check the fuses? I would bet the fuse would pop before the relays fry.

  7. #7
    Join Date
    Jul 2012
    Location
    dartmouth, NS, Canada
    Posts
    281
    My Cars
    1999 BMW 540I
    i would check the fuse my aux fan seized and when i went to look in the fuse box the fuse was black and burnt on the top

  8. #8
    Join Date
    Jun 2009
    Location
    Kansas
    Posts
    503
    My Cars
    1994 353is 1995 M3
    face palm...... Thanks guys, that's embarrassing

  9. #9
    Join Date
    Nov 2012
    Location
    USA
    Posts
    413
    My Cars
    1994 E36 325ic
    Sweet test thanx!
    I do have one question some what off topic...Why can't I simply run an aux fan of my choice, and my ac fan from the same power/ground/on off supply?

    I could probably use the same rely wiring that is on the forums and wire both fans into a rely and fuse then wire that to the plug n play fan switch in the radiator? No need to tap into obd or anything other than shotty fan.

    I have the 80c switch on the way. Everything has been done.
    my radiator blew up cuz a tire in the rode pushed the fan shroud up fan blew. Got pretty lucky id say.also, I guess Im not sure the condition of the water pump.
    How can I check that? d

  10. #10
    Join Date
    Jun 2010
    Location
    NY
    Posts
    5,871
    My Cars
    1997 328i
    You can wire it however you want, BUT you can't use the same wires that power the stock fan and also expect those wires to handle the load of the second fan. The stock fuse would blow and the stock relay would be at its limits. You can use the stock fan power wires to trigger your own relay, that would be fine, but the problem with that is if the stock fuse blows (and they do blow when the stock fan goes bad) it would prevent your new fan from running. So using your own power feed/fuse/relay is a safe bet, and you can use your own temp sensor too if you want.

    When you have things setup I suggest monitoring the temp of the radiator and when the fan's engage with a temp prob of some sort, I have one on my multimeter. You should calibrate it with ice water, mine read 3C high. Also I found that my 80/88C fan switch was not coming on soon enough, it was in the high 90c range. I ended up encapsulating my radiator temp switch with styrofoam and used duct tape and it now come on very close (off by a couple C) and I'm happy with it now.

  11. #11
    Join Date
    Aug 2008
    Location
    toronto canada
    Posts
    1,559
    My Cars
    06 Cayenne
    Im going to thread jack. Is there anyway to repair the PULLER fan that came stock on late m42 and all m44 powered cars? Mine only works in high...

  12. #12
    Join Date
    Jun 2010
    Location
    NY
    Posts
    5,871
    My Cars
    1997 328i
    I don't think its easily done. Here is a new fan on ebay to replace the OEM one, ~$50.
    http://www.ebay.com/itm/COOLING-FAN-...-/271128020997

  13. #13
    Join Date
    Nov 2012
    Location
    USA
    Posts
    413
    My Cars
    1994 E36 325ic
    Quote Originally Posted by Eric93se View Post
    You can wire it however you want, BUT you can't use the same wires that power the stock fan and also expect those wires to handle the load of the second fan. The stock fuse would blow and the stock relay would be at its limits. You can use the stock fan power wires to trigger your own relay, that would be fine, but the problem with that is if the stock fuse blows (and they do blow when the stock fan goes bad) it would prevent your new fan from running. So using your own power feed/fuse/relay is a safe bet, and you can use your own temp sensor too if you want.

    When you have things setup I suggest monitoring the temp of the radiator and when the fan's engage with a temp prob of some sort, I have one on my multimeter. You should calibrate it with ice water, mine read 3C high. Also I found that my 80/88C fan switch was not coming on soon enough, it was in the high 90c range. I ended up encapsulating my radiator temp switch with styrofoam and used duct tape and it now come on very close (off by a couple C) and I'm happy with it now.
    Thank you...I thought as much, but it I have always been a electrical cheater i suppose. Im afraid to get a permanent cEL cutting stuff under obd port. MY pedal trick already will not work. I don't wan't to create any electrical nightmares in my car, but I think that I will have to follow a few DIY and figure this relay out!

  14. #14
    Join Date
    Jun 2009
    Location
    Vermont
    Posts
    30,916
    My Cars
    97 328i Vert, 98 M3 Vert
    Wiring in a electric fan to replace the clutch fan is fairly easy. You take 12 volts off the "B" post at the fire wall. Run that to one side of a relay (think of a light switch) then connect the other side of that relay to the fan. Now all you need is a way to make the relay open and close when you want it to. Don't forget to install a fuse in the line from the B post or you risk burning out the new fan. Ground the fan motor to the chassis

    To control the realy you can tap into the wires going to the low speed side of the temp switch in the radiator. Its recomended to get a lower temp rated switch. The stock switch is designed to close only when the enigne is starting to overheat. You need a lower temp rated switch so it closes BEFORE the engine starts to overheat. Tap into the low speed/ground wires and run those to your relay.

    DONE>
    Last edited by flyfishvt; 01-20-2013 at 07:50 AM.

  15. #15
    Join Date
    Nov 2012
    Location
    USA
    Posts
    413
    My Cars
    1994 E36 325ic
    Thank you That makes mores sense. Power to the fan is cut off by the rely. The fan switch will allow power to the fan. Affirmative on the fuse!
    Convinced this mod is dangerous not done properly, I did get the 80 degree fan switch. (I did 80 degree stat when I got the car.)

    SO one real question involving relay and fuse shoping. (The fan im looing at is 3000cfm and draws 8.something amps which is a fair fan for a flexlight copy in my local small town shop.) So i need a rely for 10 amps? fuse for 10 amps as well?

    flyfishvt somehow you always are there for my questions! THANKS! BTW is your name suppose to mean fly fishing veteran?

    ok one more question. Some people are using a switched power from obd port I believe to make sure the fan does not run when the car is not running. Is that so? IS that a matter of a different rely? Maybe a rely where two conditions are need to be meet to allow the switch to open? thanks again
    Last edited by dhangjr; 01-21-2013 at 06:39 AM. Reason: Automerged Doublepost

  16. #16
    Join Date
    Jun 2010
    Location
    NY
    Posts
    5,871
    My Cars
    1997 328i
    The relay will need to be rated much higher than the power been drawn for the fan. The fuse can be closer, 10A might be too close and my blow (or may not) so 15A would be safe for that, remember your protecting the wire from shorting out and not necessarily the fan. Most Bosch relays will be 15, 20, 25, 30 amps. When it comes to the relay higher is better, because the higher the load the relay can handle the less likely the contacts will burn out, basically the higher the rating the better the quality. Cost can come into play, but generally automotive relays are cheap.

    This one is not bosch but will work fine:
    http://www.ebay.com/itm/12-VOLT-PREM...-/271135461730

    You can spend more and get a brand like bosch if you wish.

    Using the power from the diagnostic port is for the triggering of the relay not for supply the power to actually run the fan. On the relay power for the fan comes in, goes through the internal switch, then comes out and goes to the fan. Also on the relay is the solenoid that turns the power on and off, a low power source (positive) can come from the diagnostic port to the relay, then come out of the relay and go to your thermostatic switch (temp switch) and then the other side of the temp switch will go to ground.

  17. #17
    Join Date
    Aug 2011
    Location
    Norwalk, CT
    Posts
    653
    My Cars
    04 330ci ZHP, 04 Yukon
    Why not just use the wiring to the factory aux fan to power an aftermarket puller fan and eliminate the stock mechanical and aux fans? Clean up everything.

    flyfish? you seem to know everything (don't mean that in a bad way)
    Last edited by EfiniMotorsport; 01-21-2013 at 09:22 PM. Reason: Automerged Doublepost

  18. #18
    Join Date
    Jun 2009
    Location
    Vermont
    Posts
    30,916
    My Cars
    97 328i Vert, 98 M3 Vert
    Because you will not pull enough air through to cool the a/c condenser and if his electric fan is only a single speed fan you could run into issues using the 2 speed aux fan power supply. There are several excellent suggestions here. There's no need to bastard rig it. Wiring it the right way only takes a few minutes.

    Doing it your way also eliminates the aux fan as an emergency backup.
    Last edited by flyfishvt; 01-21-2013 at 09:41 PM. Reason: Automerged Doublepost

  19. #19
    Join Date
    Aug 2011
    Location
    Norwalk, CT
    Posts
    653
    My Cars
    04 330ci ZHP, 04 Yukon
    I meant wiring in a quality aftermarket puller fan (2500+ CFM, 2 speed) and replacing the stock mechanical fan. Most cars only have pullers anyway. The wiring would be easy as you would just wire it in place of the aux fan.

  20. #20
    Join Date
    Nov 2012
    Location
    USA
    Posts
    413
    My Cars
    1994 E36 325ic
    Efini that was my first question too, but is bad idea because the stock setup is probably not set up to deal with this beefy fan i will install and likely would blow fuses...
    sooooo....bla bla......ha ha......thanx eric.
    NOw thats out of the way here is how I think i will wire my rely in.
    OPINIONS PLEASE
    *Power from power block goes +IN as the main power for Rely
    *The low temp from a/c fan switch will go IN to the rely as well
    *now the positive out to the fan. (Of course ground the fan, this is some what a concern too. THe ground neds to bee good. electrolysis is not wanted!)

    any thoughts on this (my question is cutting the obd port that would be used to switch the fan on so it is always running when the car is running, sounds good even if fan burns out lil earlier.)

    http://forums.bimmerforums.com/forum...d.php?t=618192

    thanx again for all help and laughs ;-)

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •